The Possible Protective Effect of Selenium against Chromium Induced Thyroid Toxicity in Adult Male Albino Rats: Histological, Immunohistochemical and Biochemical study.

Introduction: Chromium (Cr) has thyrotoxic effects as a result of oxidative damage potency. The antioxidants as Selenium can counteract such effects.Aim of the study: to clarify the histopathological, immunological and bio-chemical changes that occur in the thyroid gland following Cr administration and the possible therapeutic role of Selenium supplementation. Material and Methods: fifty adult male albino rats were equally divided into: GІ (control) subdivided into subgroup I-A(normal): received nothing and subgroup I-B(sham-control): received normal saline (0.5 ml) IP for 5 days ; GII(selenium treated): received selenium 0.5mg/kg IP for 5days; GIII(chromium treated): received 60µg/kg I.P. for 5 days; GIV( Cr and Selenium concomitantly treated):received Cr 60µg/kg in concomitant with Selenium 0.5mg/kg IP for 5 days ; GV( Cr and Selenium serially treated):received Selenium for 5 days then Cr for another 5 days. Histological, immunohistochemical and biochemical analyses were performed on all tissues.Results: GIII showed variable pathological changes as disorganized thyroid parenchyma, ruptured follicles, empty colloid and massive hemorrhage. Administration of Selenium in GIV and GV displayed improvement of the pathological changes, results showed no significant changes between the last two groups, which means that there is no difference between administration of selenium as a protective tool in-advance or concurrently with Cr exposure.Conclusion: Selenium exerted the protective effect on thyroid gland against Cr toxicity through restoration of thyroid parenchyma and function.